The present invention relates to a harvesting head comprised of several sections for being attached to a harvester, with a middle section comprising the connection elements with which the middle section can be attached to a carrier device of the harvester, and with at least one side section which is connected by an articulated connection to the middle section and about which the side section can pivot from a lower to an upper stop, wherein the carrier device comprises a device for the height adjustment whose adjusting movements are controlled by an evaluation device which is connected to sensors which constantly measure the ground distance of one or more sections of the harvesting head during the forward travel of the harvester, the evaluation device converts the sensor signals of the sensors into adjusting commands for changing the height level of the device for adjusting the height and transfers these adjusting commands to an actuator of the device for the height adjustment. The invention also relates to a method for regulating the height of such a harvesting head.
U.S. Pat. No. 9,198,359 B2 teaches a harvesting head comprised of several sections. The height level of the harvesting head is primarily changed by an adjusting of the carrier device of the harvester, in the exemplary embodiment a combine as a harvester with an oblique transport channel as a carrier device. Usually, receptacles for a harvesting head which make possible an additional height adjustment such as, for example, standing hydraulic cylinders on which the surface rests are located on the oblique transport channel, which can be adjusted in height on its front end. These hydraulic cylinders are in the sense of this invention a possible component of the carrier device with which the height adjustment of the harvesting head can also be carried out during the harvest or in a supplementary manner. Therefore, a carrier device can have several possibilities of adjustment for setting the working height of a harvesting head, namely, for example, by the height adjustment of the oblique conveyor and by the additional adjustable carrier cylinders which can be used in particular for a rotating of the harvesting head about the longitudinal central axis.
The height adjustment is necessary in order to adapt the height level of the harvesting head during the forward travel of the harvester in the case of uneven ground conditions to the constantly changing distances of the harvesting head to the ground. If the harvesting head is too high, the harvested material can be cut to high or even not cut at all, which results in undesired losses of the harvested crops. If the harvesting head is adjusted to local, damaged can occur to the harvesting head on account of a collision of structural components of the harvesting head with the ground.
In the case of rather large working widths of the harvesting heads it is no longer sufficient to adjust the height of the harvesting head only by a height adjustment by the carrier device to a desired distance to the ground. In the case of rather large working widths the ground can have such height differences even in the direction transverse to the direction of travel of the harvester over the working width that an adaptation of the height of the side sections of the harvesting head which is separate from the middle section is necessary. In the harvesting head in document U.S. Pat. No. 9,198,349 B2 this is solved by an adjustment by motor of the bending angle between the middle section and the particular side section which takes place as a function of a distance of the side section from the ground, which distance is determined by sensors. The adjustment of the pivoting position of the side sections by motor takes place via hydraulic cylinders in which the pressure should be held at a constant level. Correspondingly changeable bending angles of the transverse axes of the side sections in comparison to the transverse axis of the middle section are adjusted in the running adjustments of the hydraulic cylinders.
EP 3 087 819 A2 teaches measuring forces acting counter to the direction of travel—that is, in the horizontal direction—on the harvesting head by sensors and in the case of rising sensor values to change the pivoting position of the side harvesting head parts relative to the middle part of the harvesting head in such a manner that the acting forces are reduced again. This procedure is disadvantageous because the changing of position of the side harvesting head parts relative to the ground is not started until the sensors are already measuring a rise of the acting forces. Damage to the harvesting head can already have occurred before the side harvesting head parts have been moved into a non-critical position of height. Even if no direct damage occurs, the harvesting head is subjected by the constant load change to increased wear. The middle part of the harvesting head is not taken into consideration in this type of height adjustment.
Furthermore, a harvesting head is known from the prior art which is produced by the Geringhoff company and is distributed under the designation of “Truflex”. In this harvesting head the side sections are supported on the ground by a wheel undercarriage. The height position of the middle section is also adapted here by the sensor-supported adjustment of the carrier device of the harvester to changing ground distances. The signals for the height adjustment are determined by touch rods which measure the distance to the ground. Since the side sections are connected to the middle section by an articulation whose articulated shaft faces in the travel direction of the harvester and the side sections are supported against the ground by their own undercarriage, the side sections can copy the contour of the ground by the undercarriage and adjust themselves in a continuous manner to an individual distance to the ground of the particular side section which corresponds to an acceptable distance in the area of the undercarriage. The undercarriage can also be adjusted in height in this harvesting head, wherein the height adjustment takes place according to the sensor signals of the associated ground touchers. However, continuously changing bending angles of the transverse axes of the side sections relative to the transverse axis of the middle section result here in particular in the case of uneven ground conditions.
The problem arises in the known harvesting heads that the mobility of the side sections is technically limited in comparison to the middle section. Once the technical limits have been reached, elevated loads act on the articulated connections. This is especially true if the terrain contour actually would require a further adaptation in height of the side sections, whether it is downward or upward, which, however, is not possible on account of the technical limits of the articulated connections. There is then the danger that the concerned side section is rammed into the ground during the further advance of the harvester and/or that structural components of the articulated connections are bent and damaged. Also, the harvesting head can be pushed onto the ground, as a result of which the carrier device with the harvester associated with it could be raised. That can lead to significant damage to the carrier device.
The present invention concerns the problem of reducing the danger of damage to the harvesting head and to the structural components of the articulated connections.